In recent years, the development of light-emitting elements, such as organic EL elements, has advanced. Also, display devices using light-emitting elements are being developed, and such display devices employ an arrangement of blue, green, and red light-emitting elements.
Considerations such as reducing electric power consumption have placed value on luminous efficiency improvements for light-emitting elements. Blue light-emitting elements in particular have low luminous efficiency in comparison to green and red light-emitting elements. As such, there is demand for improving the luminous efficiency of blue light-emitting elements.
Conventionally, technology for employing a resonator structure in a light-emitting element is known as one approach to improving the luminous efficiency. For example, Patent Literature 1 discloses a light-emitting element in which a bottom electrode (a mirror), a transparent conductive layer, a hole transport layer, a light-emitting layer, a electron transport layer, and a top electrode (a half-mirror) are layered, and further discloses adjusting the optical thickness between the mirror and the half-mirror so as to amplify the luminous efficiency (see paragraph 0012). These adjustments to the optical thickness are performed by adjusting the physical thickness of the layers making up the light-emitting element.